Westminster Police Dept(GOLDEN, Colo.) -- The teenage suspect accused of murdering and dismembering 10-year-old Jessica Ridgeway was called “intelligent and mature” by his jail supervisors and deemed fit to be held at an adult jail facility in Colorado.

Austin Sigg, 17, is accused of killing Ridgeway while she was on her way to school on Oct. 5. The fifth-grader’s body was found dismembered in a park days later.

Sigg is also accused of attempted abduction of a female jogger in a May 2012 incident in a park in Arapahoe County, Colo., where he lives. He has been held in isolation at a juvenile facility since his arrest in October.

On Tuesday, his jail supervisor, a security guard, and the supervisor of the Jefferson County adult jail all testified that because Sigg has demonstrated he is intelligent and mature, and has had no problems at the the juvenile facility, he could be safely transferred to the adult prison.

The witnesses testified that Sigg eats his meals alone and spends his time playing Sudoku.

Sigg’s attorney, a public defender, argued that because of Sigg’s small stature and the fact that other inmates could “potentially scream and yell at the child, Austin Sigg” should be kept in the juvenile facility. Judge Stephen Munsinger ruled that Sigg, who turns 18 in January, should be transferred.

Sigg, who appeared in court in a bright green jail jumpsuit, will be tried as an adult. The defense waived its right to fight for him to be tried as a juvenile in the first week after his arrest.

Nine members of Ridgeway’s family showed up for the hearing, many of them wearing the color purple, Ridgeway’s favorite color, which they have worn at each of the hearings since Sigg’s arrest.

They showed little emotion during the two-hour hearing, but were upbeat and even making jokes with their victims’ advocate and among themselves. At one point, they exchanged notes and chuckled.

Five members of Sigg’s family were also in the courtroom, including his mother. Neither Sigg nor his family showed any emotion during the hearing.